1. Field of the Invention
The present invention relates to a planar dielectric integrated circuit for use in a millimetric-wave band and a microwave band.
2. Description of the Related Art
In a millimetric-wave band and a microwave band, transmission lines have often been used which are constructed by forming a conductor on a dielectric substrate of a waveguide, a coaxial line, a microstrip line, a coplanar line, a slot line, and the like. In particular, in a dielectric substrate having a transmission line formed thereon, since connection with electronic components, such as ICs, is easy, many attempts to form an integrated circuit by mounting electronic components onto a dielectric substrate have been made.
However, in the conventional microstrip line, coplanar line, slot line, and the like, since transmission loss is relatively large, these are not suitable for a circuit requiring, particularly, a low transmission loss. Therefore, the applicant of the present invention submitted the invention concerning a planar dielectric line and an integrated circuit, which solve these problems, in Japanese Patent Application No. 07-069867.
Meanwhile, since the distribution of electromagnetic field around input/output sections of electronic components, such as semiconductor devices, and the distribution of electromagnetic field around planar dielectric lines generally differ, merely mounting electronic component onto the planar dielectric line causes the conversion loss to increase greatly. Further, if electronic components are only mounted onto one surface of the dielectric plate, no connection is made between the electro magnetic field on the back surface thereof and the electronic components, this point also leading to an increase in the conversion loss. Mounting electronic components onto both surfaces of the dielectric plate eliminates the latter problem; however, this results in a decrease in the yield, an increase in loss, and an increase in the material and mounting costs.
An object of the present invention is to provide a planar dielectric integrated circuit such that energy conversion loss between the planar dielectric line and the electronic components is small, and impedance matching between them is obtained easily.
According to the aspect of the present invention, to perform integration by reducing a signal loss in the coupled section of the planar dielectric line and the electronic components and while maintaining a low loss characteristic, which is a feature of the planar dielectric line, a planar dielectric line is formed such that two conductors are provided at a fixed distance on a first main surface of a dielectric plate to provide a first slot, two conductors are provided at a fixed distance on a second main surface of a dielectric plate to provide a second slot which opposes the first slot, with the area sandwiched between the first slot and the second slot of the dielectric plate being formed as a plane-wave propagation area. A slot line is formed at the end portion of the planar dielectric line of the dielectric plate, a line-conversion conductor pattern which is connected to the planar dielectric line and is used to perform mode conversion with the slot line is provided in the slot line, and electronic components are disposed in such a manner as to be extended over the slot line.
An RF signal of the LSM mode, which propagated through the planar dielectric line as described above, is coupled to the line-conversation conductor pattern, is converted into a TE mode, and propagated through the slot line. The signal which propagated through this slot line is inputted to the electronic components. Conversely, the signal outputted from the electronic components propagates through the slot line in the TE mode, is converted into the LSM mode by the line-conversion conductor pattern, and propagates through the planar dielectric line.
Preferably, the line-conversion conductor pattern is provided at positions on both ends of the slot line, and the electronic components are disposed in nearly the central portion of the slot line. As a result, when the signal is propagated from one planar dielectric line of the two planar dielectric lines to the other planar dielectric line, the signal is converted into the mode of the slot line at the midpoint by the line-conversion conductor pattern and the slot line, and signal conversion, for example, amplification, is performed by the electronic components, and then the signal is returned to the mode of the planar dielectric line via the line-conversion conductor pattern. Therefore, signal conversion using the electronic components is made possible with a construction with a small energy conversion loss while performing the propagation of a signal using the planar dielectric line.
Preferably, a short stub which is used to obtain impedance matching between the line-conversion conductor pattern and the electronic components is provided at the midpoint of the slot line. As a result, impedance matching is obtained between the line-conversion conductor pattern and the electronic components, and the loss in the connection section of the slot line and the electronic components is reduced.
Further, preferably, an impedance matching circuit is provided between the line-conversion conductor pattern and the slot line. As a result, impedance matching is obtained between the line-conversion conductor pattern and the planar dielectric line, and the slot line, thereby suppressing unwanted reflection and reducing the transmission loss caused by line conversion.